Use Primal Cry, followed by Black Claw and then Hunting Party. At that point Brutus should use the Pig Out ability, which shouldn't finish off your first Zandalari pet.
Use Primal Cry again, which will defeat Brutus. ZA will only be able to use Black Claw at this point before dying.
Rukus will already have the Speed Reduction and Black Claw debuffs thanks to ZA's sacrifice, so have ZK immediately use Hunting Party.
Rukus will have 1 round left with the Shattered Defenses, Black Claw, and Speed Reduction debuffs. Your ZK will also have its +25% damage racial active as well. Which means...
Use Leap and watch 'em weep!
Note: Critical strikes can wreck this strategy, so it may take more than one attempt depending on your RNG.
I used the following team to defeat Brutus and Rukus. (Make sure you have Zandalari Anklerender out first.)
Note: Critical strikes can wreck this strategy, so it may take more than one attempt depending on your RNG.